Process for the production of molecular sieving carbon

ABSTRACT

A molecular sieving carbon characterized by (A) having a structure in which a number of spherical carbonaceous particles having a particle diameter of 0.8 to 120 micrometers overlap and coalesce three-dimensionally at random, (B) in which continuous pathways running three-dimensionally at random exist between a number of the carbonaceous particles, (C) in which a number of the carbonaceous particles have each a number of micropores communicating with the pathways existing between the particles, and (D) having a carbon content of at least 85% by weight. The molecular sieving carbon is useful for obtaining, for example, a nitrogen gas, oxygen gas or gaseous mixture enriched with either the nitrogen gas or the oxygen gas from a gaseous mixture containing the nitrogen gas and oxygen gas.

This is a division of Ser. No. 07/165 525, filed Mar. 8, 1988 now U.S.Pat. No. 4,933,914.

The present invention relates to a molecular sieving carbon, process forits production and its use. More particularly, it relates to a molecularsieving carbon which is applied in the field of separating and purifyingmixed gases by the molecular sieving effect of fine pores or the like, aprocess for its production and its use.

Heretofore, as adsorbents producing the molecular sieving effect,silica-alumina type zeolites have widely been used and have played animportant role in the separation and purification of gases. The saidzeolite type molecular sieves, however, are polar and hydrophilic andinferior in thermal stability and chemical resistance, and entail thedefect that they are strong in selective adsorbability for such polarsubstances as water that they do not show the molecular sieving effectin the presence of polar substances.

Incidentally, recently, it has become possible to prepare molecularsieves using, as material, non-polar and hydrophobic carbons. Themolecular sieving carbons of this kind are excellent in thermalstability and chemical resistance, and attract attention as molecularsieves usable even in the presence of polar substances.

Japanese Patent Publication No. 37,036/1974 discloses a process ofadsorbing on activated carbon a raw material substance to make phenoltype resins or furan type resins by polymerization or condensation,causing its polymerization or condensation and then heating at 400° to1,000° C. thereby preparing a molecular sieving carbon adsorbent. Thisprocess is understood as a process of adsorbing the said synthetic resinmaterial substance along with catalyst on prepared activated carbonhaving great pores and then again treating for its carbonization.

Japanese Patent Publication No. 47,758/1977 discloses a process ofheating saran wastes at high temperatures, then pulverizing andgranulating by addition of a sintering agent, such as coal tar pitch,and a granulating agent, such as Avicell, followed by once again heatingat a temperature of 400° to 900° C. for their dry distillation. Thisprocess gains the advantage of being capable of preparing the molecularsieving carbon using inexpensive raw materials (saran wastes).

Japanese Patent Publication No. 18,675/1977 discloses a process oftreating a coke containing up to 5% of volatile components at atemperature of 600° to 900° C. for a time of 1 to 60 minutes or more byaddition of hydrocarbons releasing carbons by their thermaldecomposition thereby depositing the released carbons in pores of thecoke and thus, preparing a carbon-containing molecular sieve used forthe separation of gases having as small a molecular diameter as about 4Å or less.

Japanese Patent Publication No. 8,200/1979 discloses an apparatusdesigned for the production of oxygen-rich air by contacting air with amolecular sieving coke for selective adsorption of oxygen from the airand desorbing it under reduced pressure.

Japanese Laid-Open Patent Application No. 106,982/1974 discloses aprocess of impregnating coke with an organic compound having boilingpoints of 200° to 360° C. at normal pressure or reduced pressure therebyreducing overly great pores of the coke to 2 to 6 Å and thus, preparinga molecular sieving coke suitable for the separation of O₂ and N₂, inparticular.

Japanese Patent Publication No. 17,595/1979 discloses a process for theproduction of nitrogen-rich gases from gases containing at least oxygenin addition to nitrogen, such as air, using the molecular sieving cokeprepared by the process disclosed in the said Japanese PatentPublication No. 18,675/1977.

Japanese Patent Publication No. 54,083/1983 discloses a process ofmolding a finely-divided charcoal, not activated carbon, or coke using acoking agent and dry distilling the resultant molding thereby preparinga carbon-containing adsorptive medium, including steps of pulverizingthe charcoal, not activated carbon, or coke to a particle size of 100micrometers or less, mixing with 5 to 20% by weight of a natural and/orsynthetic rubber and 1 to 15% by weight of a thermoplastic substance,fabricating this mixture into a molding and heating the molding at about400° to 1,400° C. at an inert atmosphere.

Further, Japanese Laid-Open Patent Application No. 45,914/1984 disclosesa process of granulating a coconut shell powder using, as a binder, coaltar pitch and/or coal tar, dry distilling at 750° to 900° C., washingthe dry-distilled carbon with an aqueous rare mineral acid solution,washing with water and drying and impregnating this dried one with 1-3%coal tar pitch and/or coal tar at 200° to 400° C., then enhancing thetemperature up to 950° to 1,000° C., heat treating at this enhancedtemperature for 10 to 60 minutes and taking out a product after coolingin an inert gas thereby preparing a molecular sieving carbon.

The object of the present invention is to provide a molecular seivingcarbon having an extremely specific porous structure.

Another object of the pre invention is to provide a molecular sievingcarbon which is great in adsorption selectivity coefficient anddiffusivity ratio rate and extremely great in adsorption capacity.

Still another object of the present invention is to provide a processfor the production of the said molecular sieving carbon of the presentinvention.

Another further object of the present invention is to provide use of thesaid molecular sieving carbon of the present invention for theseparation of certain gas mixtures on the basis of the finding that thesaid molecular sieving carbon is optimum for the separation of such gasmixture.

Other further objects and advantages of the present invention will beclear from following explanations.

According to the present invention, the said objects and advantages ofthe present invention can be achieved by a molecular sieving carboncharacterized by

(A) having a structure in which a number of spherical carbonaceousparticles having a particle diameter of 0.8 to 120 micrometers overlapand coalesce three-dimensionally at random,

(B) in which continuous pathways running three-dimensionally at randomexist between a number of the carbonaceous particles,

(C) in which a number of the carbonaceous particles have each a numberof pores communicating with the pathways existing between the particles,and

(D) having a carbon content of at least 85% by weight.

FIGS. 1 and 2 of the accompanying drawings are scanning electronmicroscopic photographs of the molecular sieving carbon of the presentinvention (magnification: about 300X in FIG. 1 and about 1,000X in FIG.2).

FIG. 3 is a flow chart for the apparatus used

FIG. 3 is a flow chart for the apparatus used for the measurement ofadsorption characteristics of the molecular sieving carbon of thepresent invention.

FIG. 4 is a flow chart for the pressure swing adsorption apparatus usingthe molecular sieving carbon of the present invention as adsorbent.

Further, according to the present invention, the said molecular sievingcarbon of the present invention is prepared by a process for theproduction of a molecular sieving carbon which comprises

(1) preparing an intimate mixture comprising

(A) a finely-divided thermosetting phenol resin, said finely-dividedthermosetting phenol resin being specified as

(a) comprising primary spherical particles of a phenol resin having aparticle diameter of 1 to 150 micrometers or the said primary sphericalparticles and their secondary coagulated substance,

(b) of which at lest 50% by weight of the whole having a size capable ofpassing through a 100 Tyler mesh sieve,

(c) satisfying the following formula:

    D.sub.900-1015 /D.sub.1600 =0.2-9.0

    D.sub.890 /D.sub.1600 =0.09-1.0

in the case where in the infrared absorption spectrum by KBr tabletmethod, the absorption intensity of a peak at 1600 cm⁻¹ is expressed, asD₁₆₀₀, the absorption intensity of the greatest peak in the range of900-1015, cm⁻¹ as D₉₀₀₋₁₀₁₅, and the absorption intensity of a peak at890 cm⁻¹ as D₈₉₀, and

(d) having a solubility in methanol under reflux of 50% by weight orless,

(B) a solution of a thermosetting resin of which the thermosetting resinbeing a phenol resin or melamine resin, and

(C) a high polymer binder, said high polymer binder being selected frompolyvinyl alcohols and water-soluble or water-swellable cellulosederivatives,

said intimate mixture containing 5 to 50 parts by weight (as solids) ofthe solution of the thermosetting resin (B) and 1 to 30 parts by weightof the high polymer binder (C) per 100 parts by weight of thefinely-divided thermosetting phenol resin (A),

(2) molding the said intimate mixture into a particulate substance, and

(3) heat treating the particulate substance at a temperature falling inthe range of 500° to 1,100° C. under a non-oxidizing atmosphere therebyforming a carbonized particulate product.

The finely-divided thermosetting phenol resin (A) used in the step (1)in the process of the present invention is composed of primary sphericalparticles of a phenol resin having a particle diameter of 1 to 150micrometers or the said primary spherical particles and their secondarycoagulated substance. The primary spherical particles should preferablyhave a particle diameter falling in the range of 2 to 80 micrometers.

Further, at least 50% by weight of the said fine powder (A) as a wholehas a size capable of passing through a 100 Tyler mesh sieve. Morepreferably, at least 90% by weight of the fine powder (A) has a sizecapable of passing through a 100 Tyler mesh sieve. The fine powder (A)contains methylol groups in adequate but considerable proportions. Thatis, the fine powder (A) satisfies the following formula:

    D.sub.900-1015 /D.sub.1600 =0.2-9.0, and

    D.sub.890 /D.sub.1600 =0.09-1.0

in the case where in the infrared absorption spectrum by KBr tabletmethod, the absorption intensity at 1600 cm⁻¹ (absorption peakascribable to the benzene) is expressed as D₁₆₀₀, the greatestabsorption intensity in the range of 900-1015 cm⁻¹ (absorption peakascribable to the methylol group) as D₉₀₀₋₁₀₁₅, and the absorptionintensity at 890 cm⁻¹ (absorption peak of the isolated hydrogen atom inthe benzene nucleus) as D₈₉₀.

The value of a ratio of D₉₀₀₋₁₀₁₅ /D₁₆₀₀ falls preferably in the rangeof 0.3 to 7.0 and more preferably in the range of 0.4 to 5.0.

Moreover, the fine powder (A) is also specified as having a solubilityin methanol under reflux of 50% by weight or less.

The methanol solubility referred to here is determined by the followingformula by precisely weighing about 100 g of a sample (theprecisely-weighed weight is called C), heat-treating in about 500 ml of100% methanol under reflux for 30 minutes, then filtering through aglass filter, further washing the filter residue sample with about 100ml of methanol on the filter and then drying the filter residue sampleat a temperature of 100° C. for 2 hours (the precisely-weighed weight iscalled D). ##EQU1##

The methanol solubility defined by the above formula is the property ofthe said finely-divided phenol resin (A) that exhibits itself by itshaving a structure that it is properly controlled for its crosslinkdensity and contains a considerably great amount of methylol groups.

That is, when the crosslink density is lower and the content of methylolgroups is greater, the methanol solubility is greater and on thecontrary, when the crosslink density is higher and the content ofreactive methylol groups is reduced, the methanol solubility goes lower.The methanol solubility of the finely-divided phenol resin (A) used inthis invention is preferably 1 to 40%, and more preferably 2 to 35%.

The finely-divided phenol resin (A) used in the present invention can beprepared by contacting phenols with a hydrochloric acid-formaldehydebath containing hydrochloric acid (HCl) in a concentration of 5 to 28%and formaldehyde (HCHO) in a concentration of 3 to 25% maintaining thebath so as to reach 8 or more in a bath ratio represented by thefollowing formula (I) ##EQU2## said contact being effected in such amanner that a white turbidity is formed after phenols are contacted withthe bath and then at least spherical pink solids are formed.

As the phenols phenol is most favorable, but provided that at least 70%by weight (called "%" for short hereinafter), and particularly at least75%, of phenols is contained, they may be mixtures with one or more ofknown phenol derivatives, such as o-cresol, m-cresol, p-cresol,bis-phenol A, o-, m- or p-C₂ -C₄ alkylphenol, p-phenylphenol, xylenol,hydroquinone or resorcin and the like. The feature of the abovemanufacture method lies in contacting an aqueous hydrochloricacid-formaldehyde solution obtained by setting hydrochloric acidconcentrations in considerably high concentrations and containing anexcess of formaldehyde with respect to phenol with phenol at a bathratio of 8 or more and preferably at as great a ratio as 10 or more.Such phenol-formaldehyde reaction conditions differ basically from knownnovolak resin and resol resin reaction conditions. That is, as comparedwith conventional novolak resin production, they are the same in therespect of using acid catalyst, but they differ in the respect that inthis manufacture method, the concentration of the acid catalyst isconsiderably higher and the formaldehyde concentration as well isconsiderably higher as compared with the novolak resin production. Thatis, the novolak resin is usually prepared by reacting phenol andformalin in the presence of such an acid catalyst as oxalic acid(usually 0.2 to 2%) in condition of such an excess of phenol as to reach1/0.7 to 1/0.9, for instance, in a molar ratio (A)/(B) of phenol (A) andformaldehyde (B). The novolak resin obtained by such a method is basedon tri- to pentamers containing phenol nuclei linked by methylenegroups, and contains hardly any activity-rich methylol groups.Consequently, the novolak resin per se is not self-crosslinkable and isthermoplastic. Such novolak resins become setting resins by reactingunder heat with a crosslinking agent being a formaldehyde-generatingagent in itself while at the same time as being an organic base(catalyst)-generating agent, such as hexamethylenetetramine (hexamine),or by heat reacting after mixing, for instance, with a solid acidcatalyst and paraformaldehyde and the like. Consequently, with thedifference in the manufacture method the finely-divided phenol resin (A)used in the present invention differs completely from novolak resins.

Further, as compared with conventional production of resol resins, theyare the same in the respect of using of an excess of formaldehyde, butunlike the production of resol resins, acid catalysts are used.

Resol resins are prepared by causing the reaction by setting a molarratio (A)/(B) of phenol (A) to formaldehyde (B) at conditions of such anexcess of formaldehyde as to be 11/2 in the presence of a basic catalyst(about 0.2 to 2%), such as sodium hydroxide, ammonium and organic amine.Resol resins so obtained are based on mono- to trimers of phenolscontaining relatively great amounts of activated methylol groups, andbecause of their extremely great reactivity they are usually used as 60%or less, as solids, of an aqueous or methanol solution These resolresins, because of extremely high reactivity, cannot be solids beingstabilized over a prolonged period of time as a granule or powder, andtheir cured substances, because of a high degree of progress of theirthree-dimensional structure, are greater in hardness, and it is verydifficult to turn them into a fine powder.

Consequently, the finely-divided phenol resin (A) used in the presentinvention differs altogether from resol resins.

The said manufacture method of the fine powder (A) used in the presentinvention is disclosed, for instance, in Japanese Laid-Open PatentApplication No. 177,011/1982 and 111,822/1983.

The fine powder (A) used in the present invention generally has thecharacteristics that a weight increase ratio in acetylation is 23 to80%. The weight increase ratio in acetylation referred to here isdetermined by the following formula by precisely weighing about 10 g ofa dried sample (the precisely-weighed weight is called A), adding thisprecisely-weighed sample in about 300 g of an acetylation bathcomprising 78% acetic anhydride, 20% acetic acid and 2% o-phosphoricacid, then heating by enhancing the temperature from room temperature upto 115° C. in 45 minutes, further holding at 115° C. for 15 minutes,then quenching, suction filtering on a glass filter, thoroughly washingwith deionized water on the filter, then washing with a small amount ofcold methanol, drying the filter residue at 70° C. for 2 hours andfurther leaving in a desiccator for 24 hours (the dried weight of thefilter residue is called B). ##EQU3##

The said characteristics that the said weight increase ratio inacetylation is 23 to 80% indicate the fact that the phenol resin powdercontains methylol groups and acetylable phenolic hydroxyl groupscorresponding to the said weight increase ratio in acetylation.

The solution of the thermosetting resin (B) being another raw materialused in the step (1) in the process of the present invention is asolution of a phenol resin or melamine resin.

As the solution of the phenol resin there are cited, for instance,liquid resol resins or novolak resins. Resol resins are initial productsobtained by reacting phenols and aldehydes in the presence of basiccatalysts, and usually they are self-heat-crosslinkable phenol resinswith molecular weight about 600 or less being enriched with methylolgroups. Usually, they are often used as liquid resins in methanol oracetone as solvent, but they are also used as water-soluble resol resinmaintaining in stabilized water-soluble condition initial condensatesobtained by reacting 1.5 to 3.5 moles of aldehydes for 1 mole of phenolin the presence of a somewhat excess of an alkali catalyst. As curingcatalysts to accelerate the curing of resol resins there may be usedinorganic acids, such as sulfuric acid, hydrochloric acid and the like,and organic acids, such as oxalic acid, acetic acid, paratoluenesulfonicacid, maleic acid, malonic acid and the like. Novolak resins, asmentioned above, are obtained by reacting phenol and formalin in thepresence of an acid catalyst, such as oxalic acid, formic acid,hydrochloric acid and the like, in condition of such an excess of phenolas to reach 1/0.7 to 1/0.9, for instance, in a molar ratio of phenolsand aldehydes. They may be fed as liquid resins in methanol, acetone andthe like as solvent. These novolak resins can be cured by reacting underheat by addition of hexamethylenetetramine (hexamine).

Melamine resins are initial melamine-formaldehyde condensates andbecause of being water-soluble they can be used as aqueous solutions. Ascuring agents for melamine resins there can be used inorganic acids,such as hydrochloric acid, sulfuric acid and the like, carboxylateesters such as dimethyl oxalate esters, and hydrochlorides of aminessuch as ethylamine hydrochloride and triethanolamine hydrochloride.

Furthermore, the high polymer binder used in the said step (1) ispolyvinyl alcohols or water-soluble or water-swellable cellulosederivatives. As polyvinyl alcohols there are favorably used those whichhave a polymerization degree of 100 to 5,000 and saponification degreeof 70% or more. There are also favorably used those which are in partmodified with carboxyl groups.

Further, as cellulose derivatives there are favorably used, forinstance, methyl cellulose, carboxymethyl cellulose, hydroxypropylmethylcellulose and the like. Cellulose derivatives can be used as havingvarious viscosities according to the amount of methoxy groups (--OCH₃)or hydroxypropoxy groups (--OC₃ H₆ OH) introduced, polymerization degreeand the like.

The step (1) in the process of the present invention is carried out bymixing the said finely-divided thermosetting phenol resin (A), solutionof the thermosetting resin (B) and high polymer binder (C).

On that occasion, 5 to 50 parts by weight, as solids, of the solution ofthe thermosetting resin (B) and 1 to 30 parts by weight of the highpolymer binder (C) are used for each 100 parts by weight of thefinely-divided thermosetting phenol resin (A). Further, preferably 7 to40 parts by weight, and more preferably 10 to 30 parts by weight, of thesolution of the thermosetting resin (B), and preferably 2 to 20 parts byweight, and more preferably 3 to 15 parts by weight, of the high polymerbinder are used per 100 parts by weight of the finely-dividedthermosetting phenol resin (A).

For the mixture of the components (A), (B) and (C) the said components(A), (B) and (C) may be mixed as such, or they may also be intimatelymixed in the presence of water by adding water, for instance, beside thecomponents (A), (B) and (C). Water may also be added, for instance, ascomponent (C) dissolved in water before the components (A), (B) and (C)are mixed. Water is used preferably in amounts of 5 to 30% by weight,and more preferably 8 to 20% by weight, based on the intimate mixture(as solids) obtained in the step (1).

In the case, further, of carrying out the step (1) in the process of thepresent invention, in addition to the components (A), (B) and (C), theremay be used, for instance, starch, its derivative or modified substancein amounts of 5 to 50 parts by weight, and more preferably 10 to 40parts by weight, per 100 parts by weight of the finely-dividedthermosetting phenol resin (A).

As the said compounds, such as starch, there may be used starch such aspotato starch and corn starch; starch derivatives, for instance,esterified starch such as starch acetate, starch sulfate and starchphosphate; etherified starch such as hydroxyalkyl starch andcarboxymethyl starch; crosslinked starch such as distarch phosphate andglycerol distarch, or modified starch such as enzyme-modified dextrin,and the like. These components, such as starch and the like, functionfavorably as pore-forming materials, and are believed to participate inthe formation of pores due to the herein-below-described thermaldecomposition at the time of carbonization in a non-oxidizingatmosphere. These components may be used, in the step (1), in conditionwhere they were powder, or dispersed in water as powder, or in conditionwhere they were heat treated with hot water, such as alpha-conversiontreatment or the like.

Further, in the production of the molecular sieving carbon of thepresent invention, for instance, surface active agents such as ethyleneglycol, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether,ammonium polycarbonate and so on, curing agents for liquid thermosettingresins, crosslinking agents for polyvinyl alcohols, plasticizers forextrusion granulation, finely-divided crystalline cellulose,finely-divided coconut shell, finely-divided coal, tar, pitch or othersynthetic resins may be added in small amounts for the improvement ofworkability in the range not to lose its characteristics.

For the preparation of the intimate mixture in the step (1) the said rawmaterials can be mixed, for instance, in a ribbon mixer, V type mixer,cone mixer, kneader and the like.

For instance, the step (1) can be carried out by dry mixing apredetermined amount of the finely-divided thermosetting phenol resin(A) optionally by addition of starch and the like in these mixers andthen thoroughly mixing by addition of a predetermined amount of thesolution of the thermosetting resin (B) and the high polymer binder (C),such as polyvinyl alcohol, prepared beforehand by dissolving in hotwater.

According to the process of the present invention the intimate mixtureprepared in the step (1) is then molded into a particulate substance inthe step (2). The molding of the particulate substance is effected, forinstance, by means of mono- or bi-axial wet extrusion granulator,vertical type granulator, such as basket RYUZER (pelletizer), semi-drytype disk pelletizer and the like.

The granulate substance granulated by means of wet extrusion granulator,in particular, is favorable because of being greater in particlestrength as well as of being greater in separability of the carbonizedmolecular sieving carbon. The form of the particulate substance is, forinstance, columnar or spherical. The size of the particulate substanceobtained by the granulation in the step (2) is not particularlyrestricted, but in the case, for instance, of its being columnar, itshould preferably be of the order of 0.5 to 5 mm in diameter and 1 to 10mm in length, whereas in the case of its being spherical, it shouldpreferably be of the order of 0.5 to 10 mm in diameter.

The particulate substance formed in the step (2) is then heat treated ata temperature falling in the range of 500° to 1,100° C. under anon-oxidizing atmosphere in the step (3) whereby a carbonizedparticulate product is formed.

The non-oxidizing atmosphere may be, for instance, N₂, Ar or He.

In the case where the heat treatment temperature in the step (3) islower than 500° C., there is a great tendency that all that are obtainedare carbonized products which are smaller in specific surface area, notsufficient in adsorption capacity and lower in adsorption selectivity,and in the case where the said temperature is higher than 1,100° C.,carbonized products obtained cause the shrinkage of pores and after all,there is likewise a great tendency that all that are obtained arecarbonized products which are reduced in specific surface area andmicropore volume with lower adsorption capacity.

The preferred heat treatment temperature in the step (3) is 600° to1,000° C., and the more preferred heat treatment temperature is 650° to950° C.

Furthermore, until the heat treatment in the step (3) is reached,temperature-enhancing rate is preferably 5° to 300° C./hr and morepreferably 10° to 180° C./hr and most preferably 15° to 120° C./hr.

According to the present invention, successively to the step (3), thecarbonized particulate product can be heat treated at a temperaturefalling in the range of 500° to 1,100° C. under an oxidizing atmosphereuntil the carbonized particulate product is reduced in weight in therange up to 15% by weight.

The oxidixing atmosphere may be, for instance, air, H₂ O, CO₂ or thelike.

The heating temperature in the oxidizing atmosphere is preferably 600°to 1,000° C. and more preferably 650° to 950° C.

Thus, according to the present invention, as mentioned above, there isprovided a molecular sieving carbon characterized by

(A) having a structure in which a number of spherical carbonaceousparticles having a particle diameter of 0.8 to 120 micrometers overlapand coalesce three-dimensionally at random,

(B) in which continuous pathways running three-dimensionally at randomexist between a number of the carbonaceous particles,

(C) in which a number of the carbonaceous particles have each a numberof micropores communicating with the pathways existing between theparticles, and

(D) having a carbon content of at least 85% by weight.

The structural features of (A) and (B) above with the molecular sievingcarbon of the present invention are well expressed in scanning electronmicroscopic photographs of the accompanying FIGS. 1 and 2.

In the molecular sieving carbon of the present invention a number ofspherical carbonaceous particles have a particle diameter of 2 to 80micrometers.

Further, for the characteristic of (B) above, in the molecular sievingcarbon of the present invention, continuous pathways existing between anumber of carbonaceous particles should preferably have an averagediameter of 0.1 to 20 micrometers.

In the molecular sieving carbon of the present invention, coupled withthe said features (A) and (B), a number of the carbonaneous particleshave each a number of micropores communicating with the pathwaysexisting between the said particles. The existence of a number of thesemicropores contribute greatly to the exhibition of selectiveadsorbability of the molecular sieving carbon of the present invention.

The micropores in a number of the carbonaceous particles shouldpreferably have an average diameter of about 10 Å or less.

Moreover, the volume accounted for by micropores is preferably 0.1 to0.7 cc, more preferably 0.15 to 0.5 cc, and most preferably 0.2 to 0.4cc, per gram of weight of the molecular sieving carbon.

The molecular sieving carbon of the present invention, as the feature incomposition, has the carbon content of at least 85% by weight, andpreferably at least 90% by weight.

As is understood from the said manufacture process, in the molecularsieving carbon of the present invention a number of the said sphericalcarbonaceous particles are believed to be derived from sphericalparticles of a phenol resin having a particle diameter of 1 to 150micrometers.

The molecular sieving carbon of the present invention should preferablyhave a porosity of 25 to 50% by volume, and more preferably 30 to 45% byvolume.

The molecular sieving carbon of the present invention should preferablyhave a bulk density of 0.7 to 1.2 g/cc, and more preferably 0.8 to 1.1g/cc.

The molecular sieving carbon of the present invention, as mentionedabove, should preferably have

micropores with an average diameter of 10 Å or less, and thesemicropores should preferably be most greatly distributed in the range ofaverage diameter 3 to 5 Å. Further, it can also be said to becharacteristic of the molecular sieving carbon of the present inventionthat it contains pores greater than this, such as pores with an averagediameter of 15 to 200 Å, in as small a pore volume as to be usually 0.2cc/g or less, preferably 0.15 cc/g or less, and more preferably 0.1 cc/gor less.

The molecular sieving carbon of the present invention has a specificsurface area, as values measured by the B.E.T. method by N₂ adsorption,of the order of usually 5 to 600 m² /g, preferably 10 to 400 m² /g, andmost preferably 20 to 350 m² /g.

In this regard, usually-used activated carbon having a specific surfacearea of 1,000 to 1,500 m² /g has the maximum value of the pore sizedistribution of micropores in the range of the order of 15 Å or more inpore diameter, and the volume of pores having a pore diameter falling inthe range of 15 to 200 Å is of the order of 0.4 to 1.5 cc/g, and it doesnot have such molecular sieve characteristics as with the molecularsieving carbon of the present invention.

The molecular sieving carbon of the present invention is usuallyprovided, for instance, in a columnar or spherical form. The molecularsieving carbon of the present invention is in a 0.5 to 5 mm across and 1to 10 mm long columnar or 0.5 to 10 mm across spherical form.

The molecular sieving carbon of the present invention, as mentionedabove, can very readily be prepared, and has superior adsorptioncapacity and selective adsorption characteristics. Because of this, themolecular sieving carbon of the present invention can be used for theseparation of various mixed gases. It can be used for the separation of,for instance, a gaseous mixture of nitrogen gas and oxygen gas, gaseousmixture of methane gas and hydrogen gas, mixture of hydrocarbon isomers,such as xylene isomer, butane isomer, butene isomer and the like,mixture of ethylene and propylene, gaseous mixture of hydrogen andcarbon monoxide, gaseous mixture containing argon, and the like. Morespecifically, it can be used, for instance, for obtaining a nitrogengas, oxygen gas or gaseous mixture enriched with either the nitrogen gasor the oxygen gas from a gaseous mixture containing the nitrogen gas andoxygen gas, or for obtaining a methane gas, hydrogen gas or gaseousmixture enriched with either the methane gas or hydrogen gas from agaseous mixture containing the methane gas and hydrogen gas.

Because of this, it is desirable to employ the pressure swing adsorptionmethod. By this method, other than the above, there can be carried outthe recovery of hydrogen from steam reforming gas, ethylene plantoffgas, methanol decomposition gas, ammonia decomposition gas, cokefurnace exhaust gas and the like, or the recovery of carbon monoxidefrom converter exhaust gas, and the like, which can produce favorableresults.

In the next place, the measurement methods used in the present inventionwill be indicated hereinunder,

(1) Measurement of the pore volume and pore size distribution

The pore volume and the pore size distribution of the molecular sievingcarbon of the invention are measured by a mercury penetration methodusing a porosimeter (Poresizer 9310 made by Shimazu Seisakusho) forpores with a diameter ranging of from 60 Å to 500 micrometers.

For pores with a diameter of less than 60 Å, they are determined by thefollowing Kelvin equation from the adsorption isotherm of nitrogen gas.##EQU4## P: saturated vapor pressure of the gas when it is adsorbed topores P_(o) : saturated vapor pressure of the gas in a normal condition

γ: surface tension

V: volume of one molecule of liquid nitrogen

R: gas constant

T: absolute temperature

r_(k) : the Kelvin radius of the pores

Correction for the Kelvin radius of pores was made by theCranston-Inkley method.

(2) Gas concentration analysis

Analyzed using Shimazu gas-chromatograph GC-9A and oxygen concentrationanalyzer (Model 0260) made by Beckman Co.

The present invention will be explained in more detail with thereference to Examples hereinunder. In Tables, marks indicated in overallevaluations are ranked in the following order:

Good ⊚>◯>X not good.

EXAMPLE 1

Charged into a 400 liter reaction vessel was 300 kg of a mixed aqueoussolution of 18% hydrochloric acid and 9% formaldehyde, and thetemperature was set at 20° C. Then, in this reaction vessel 12 kg of 90%concentration of an aqueous phenol solution (20° C.) prepared by the useof 98% concentration (2% water) of phenol and water was added. After itsaddition the mixture was stirred for 30 to 40 seconds, and the contentsof the reaction vessel turned turbid rapidly, stirring wassimultaneously stopped and it was left alone. On continued standing theinner temperature was slowly enhanced, the contents discolored slowly toa light pink and 30 minutes after it went turbid, a slurry-like orresinous product was observed to form. The above reaction was repeatedfor 6 batches, and for the remaining 5 batches, excepting for the firstbatch (Referential Example), of them, following on the said step, thetemperature of the contents was successively enhanced up to 75° to 65°C. in 30 minutes, and with stirring at this temperature the contentswere held for a given period of time as indicated in Table 1. Then, thecontents were washed with water, then neutralized for 6 hours at 50° C.in 0.1% concentration of an aqueous ammonia solution, then washed withwater, filtered and dried at 80° C. for 6 hours. As a result, there wasobtained the intended phenol resin powder being spherical in particleform. Solubility in methanol under reflux (called methanol solubilityhereinafter) of this phenol resin powder was measured according to thesaid test method.

Then 10 kg of the spherical phenol resin powder of each batch preparedby the said procedure was weighed, and further, with regard to 100 partsby weight of this spherical phenol resin powder 16 parts by weight, assolids, of a water-soluble resol resin (SHONOL, BRL-2854, a product ofShowa Highpolymer Co., Ltd., solids concentration 60% by weight), 2.7parts by weight of polyvinyl alcohol with a polymerization degree of1,700 and saponification degree of 88%, 1.3 parts by weight of polyvinylalcohol with a polymerization degree of 500 and saponification degree of99% and 13 parts by weight of potato starch were weighed.

Of the said raw materials, first, the spherical phenol resin powder andpotato starch were dry mixed for 15 minutes in a kneader. On the otherhand, the said polyvinyl alcohol was dissolved with hot water so as tobecome 15% by weight of an aqueous solution, and this polyvinyl alcoholsolution and the water-soluble resol resin were added in a kneader andfurther mixed for 15 minutes.

This mixed composition was extruded by a biaxial extrusion-granulator(Pelleter-Double, EXDF-Model 100, made by Fuji Paudal K. K.) andgranulated into granular substances 3 mmφ in average particle size x 6mmL. The granulated substances were heat treated at 80° C. for 24 hours,then 500 g each of the granular substances were taken and put in arotary kiln 100 φ×1,000 mmL in effective size, the temperature wasenhanced at 60° C./hr under a nitrogen atmosphere and they were held at750° C. for 1 hour and then the kiln was cooled whereby particulatecarbonized products were obtained.

In order to evaluate the molecular sieving characteristics of thisparticulate carbonized product amounts of nitrogen gas and oxygen gasadsorbed were measured by means of adsorption characteristic measuringapparatus shown in FIG. 3. In FIG. 3 about 13 g of a sample was chargedinto a sample chamber 4 (226.9 ml), valves 11, 8 were closed, valves 2,3 were opened to deaerate for 30 minutes, then the valves 2, 3 wereclosed, the valve 11 was opened to forward oxygen gas or nitrogen gasinto a control chamber 5 (231.7 ml), when a set pressure (6.88 kg/cm²)was reached, the valve 11 was closed, the valve 3 was opened to measurethe change of the inner pressure in a predetermined period of timewhereby adsorption rate of each of oxygen and nitrogen was determined.Nitrogen and oxygen separation functions were determined by the amountof nitrogen adsorbed (Q_(l)) and amount of oxygen adsorbed (Q₂) 1 minuteafter adsorption was initiated and the difference in adsorbed amount(ΔQ) represented by the following equation (II)

    ΔQ=Q.sub. 2 -Q.sub.1                                 (II)

and the selectivity coefficient of the following equation (III) ##EQU5##in which P₁ is a nitrogen adsorption pressure and P₂ is an oxygenadsorption pressure.

The results of the above Example 1 were indicated in Table 1.

In this connection, in FIG. 3, 1 . . . vacuum pump, 2, 3, 8, 11, 12 and13 . . . valve, 4 . . . sample chamber, 5 . . . control chamber, 6 and 7. . . pressure sensor, 9 . . . recorder, 10 . . . pressure gauge, 14 and15 . . . gas regulator, 16 . . . nitrogen cylinder and 17 . . . oxygencylinder.

                                      TABLE 1                                     __________________________________________________________________________                        Example 1            Refer-                                                   Sample                                                                            Sample                                                                            Sample                                                                            Sample                                                                             Sample                                                                            ential                                                   1   2   3   4    5   Example                              __________________________________________________________________________    Phenol resin powder                                                           Holding time at 75° C. (minute)                                                            10  20  30  40   60   0                                   IR intensity                                                                  D.sub.1             1.21                                                                              1.22                                                                              1.11                                                                               0.91                                                                               0.83                                                                              1.22                                D.sub.2             0.12                                                                              0.13                                                                              0.11                                                                               0.09                                                                               0.08                                                                              0.19                                Methanol solubility (%)                                                                           32  16   5   2.4 0.5 75                                   Average particle diameter (μm)                                                                 28  27  29  28   29  26                                   Particulate carbonized product                                                O.sub.2 adsorption                                                            Adsorption pressure (kg/cm.sup.2)                                                                  3.191                                                                             3.170                                                                             3.020                                                                              2.956                                                                             3.125                                                                             3.291                               Adsorbed amount (mg/g)                                                                            16.3                                                                              18.6                                                                              23.7                                                                              26.0 19.1                                                                              12.3                                 N.sub.2 adsorption                                                            Adsorption pressure (kg/cm.sup.2)                                                                  3.471                                                                             3.413                                                                             3.410                                                                              3.556                                                                             3.500                                                                             3.321                               Adsorbed amount (mg/g)                                                                            4.1 5.9 6.4  3.1 2.7 9.6                                  Difference in adsorbed amountΔQ (mg/g)                                                      12.2                                                                              12.7                                                                              17.3                                                                              22.9 16.4                                                                              2.7                                  Selectivity coefficient α                                                                   4.3 3.4 4.2 10.1 7.9 1.3                                  Overall evaluation  ◯                                                                     ◯                                                                     ◯                                                                     ⊚                                                                   ◯                                                                     X                                    __________________________________________________________________________     Note: IR intensity ratios D.sub.1 and D.sub.2 were calculated by the          following equations. D.sub.1 = D.sub.900-1015 /D.sub.1600, D.sub.2 =          D.sub.890 /D.sub.1600                                                    

As indicated in Table 1, in the case of using, as raw material, thespherical phenol resin powder having a methanol solubility of 50% orless, particulate molecular sieving carbons having good separabilitycould be obtained.

Further, Referential Example uses, as the spherical phenol resin powderbeing raw material, one which is in excess of 50% by weight in methanolsolubility with a lower crosslink degree, and the molecular sievingcarbon obtained is considerably inferior in functions.

EXAMPLE 2

A predetermined amount of polyvinyl alcohol having a polymerizationdegree of 1,000 and saponification degree of 88% was dissolved with hotwater to make 20% by weight of an aqueous solution.

Separately from this, a spherical phenol resin powder having a methanolsolubility of 2.4% with an average particle diameter of 28 micrometersprepared in like manner as the sample 4 in Example 1, water-solubleresol resin (SHONOL BRL-2854, a product of Showa Highpolymer Co., Ltd.,solids concentration 60% by weight), water-soluble melamine resin(Sumitex Resin M-3, a product of Sumitomo Chemical Co., Ltd., solidsconcentration 80% by weight), methyl cellulose powder (METHOLOSE,60SH-4000, a product of Shin-etsu Chemical Industry Co., Ltd.), potatostarch and ethylene glycol were weighed for their respectivepredetermined amounts.

The said spherical phenol resin powder, potato starch and methylcellulose powder were dry mixed for 15 minutes in the kneader, thenaqueous polyvinyl alcohol solution, water-soluble resol resin,water-soluble melamine resin and ethylene glycol were added and furthermixed for 15 minutes. This mixed composition was extruded by means ofbiaxial extrusion granulator (Pelleter-Double Model EXDF-100 made byFuji Paudal K. K.) and columnar pellets having 6 kinds of compositionsindicated in Table 2 were prepared. These columnar pellets were 3 φ inaverage particle size ×6 mmL. These pellets were hardened and dried at80° C. for 24 hours, then 500 g of the pellets were put in the rotarykiln 100 φ×1,000 mmL in effective size, the temperature was enhanced upto 900° C. at 10° C./hr under 2 liters/min. of a nitrogen stream, theywere held at this temperature for 1 hour and then the kiln was cooled.

Nitrogen and oxygen separation functions of particulate carbonizedproducts so obtained were measured in like manner as in Example 1. Theresults were indicated in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                     Sample                                                                        6    7   8    9   10  11                                     __________________________________________________________________________    Spherical phenol resin powder                                                                  100  100 100  100 100 100                                    B                                                                             Water-soluble resol resin                                                                      48   2.9 11.8 8.8 5.9 1.1                                    (solids)                                                                      Melamine resin (solids)                                                                        24   1.5  5.4 3.8 2.4 1.1                                    C                                                                             Water-soluble high polymer binder                                             Polyvinyl         6   10.3                                                                               2.9 3.0 2.4 1.1                                    alcohol                                                                       Methyl cellulose  4   25  11.8  0  --   0                                     D                                                                             Starch           18   7.4 14.7 10  7.1 2.1                                    Sub-total        200  147.1                                                                             146.6                                                                              125.6                                                                             117.8                                                                             105.4                                  E                                                                             Ethylene glycol   2   1.5  1.5 1.3 1.2 1.1                                    F                                                                             Water*           80   43.5                                                                              20.8 18.8                                                                              17.7                                                                              15.8                                   Water ratio F/A + B + C + D                                                                    0.40  0.296                                                                              0.142                                                                             0.15                                                                              0.15                                                                              0.15                                  Workability at the time of                                                                     X    Δ                                                                           ◯                                                                      ⊚                                                                  ◯                                                                     ◯                          granulation      Impos-                                                                        sible to                                                                      granulate                                                    O.sub.2 adsorption                                                            Adsorption pressure                                                                            --    3.420                                                                              3.118                                                                             2.976                                                                             3.068                                                                             3.148                                 (kg/cm.sup.2)                                                                 Adsorbed amount  --   6.8 19.4 25.5                                                                              21.6                                                                              17.7                                   (mg/g)                                                                        N.sub.2 adsorption                                                            Adsorption pressure                                                                            --    3.555                                                                              3.418                                                                             3.523                                                                             3.481                                                                             3.245                                 (kg/cm.sup.2)                                                                 Adsorbed         --   1.0  5.8 2.2 3.7 12.4                                   amount (mg/g)                                                                 Difference in adsorbed amount                                                                  --   5.8 13.6 23.3                                                                              17.9                                                                              5.3                                    ΔQ (mg/g)                                                               Selectivity coefficient α                                                                --   7.1  3.7 13.7                                                                              6.6 1.5                                    Overall evaluation                                                                             X    X   ◯                                                                      ⊚                                                                  ◯                                                                     X                                      __________________________________________________________________________     *The amount of water is a total amount of water in watersoluble resol         resin and watersoluble melamine resin, polyvinyl alcohol dissolving water     plus water added separately for adjustment of viscosity in the case of        samples 6, 10 and 11.                                                    

In Table 7 2, sample 6 was no good in workability at the time ofgranulation and its granulation was impossible. In sample 7 using thewater-soluble high polymer binder in greater amounts than in thestipulated proportions of the present invention, it was found to be lessin amount of O₂ adsorbed and not to be favorable as the molecularsieving carbon.

Samples 8, 9 and 10 were favorable in amounts of N₂ and O₂ adsorbed andtheir separation characteristics obtained and particularly sample 9 wasexcellent in characteristics.

Sample 11 obtained from the raw material composition falling outside thelimits provided for in the process of the present invention was found tobe unfavorable because of being smaller in difference in N₂ and O₂adsorbed amount as well as in selectivity coefficient.

EXAMPLE 3

Columnar pellet precursors 3 mmφ in average particle size ×6 mmLgranulated using the same composition and the same conditions as withsample 9 in Example 2 were put in the rotary kiln 100φ×1,000 mmL, thetemperature was enhanced up to a given temperature at a temperatureenhancing rate of 15° C./hr while passing 3 liters/min, of nitrogen,they were held at this temperature for 30 minutes and then the kiln wascooled whereby carbonized products were obtained.

Nitrogen and oxygen separabilities of the carbonized products wereindicated in Table 3.

                  TABLE 3                                                         ______________________________________                                                       Sample                                                                        12    13     14     15   16                                    ______________________________________                                        Carbonization temperature °C.                                                           450     700    950  1050 1200                                O.sub.2 adsorption                                                            Adsorption pressure                                                                             3.533  3.170  3.013                                                                              3.211                                                                              3.415                               (kg/cm.sup.2)                                                                 Adsorbed amount  7.9     18.6   23.8 15.6 7.1                                 (mg/g)                                                                        N.sub.2 adsorption                                                            Adsorption pressure                                                                             3.991  3.455  3.565                                                                              3.682                                                                              3.695                               (kg/cm.sup.2)                                                                 Adsorbed         6.9     4.5    3.4  0.58 0.16                                amount (mg/g)                                                                 Difference in adsorbed amount                                                                  1.0     14.1   20.4 15.02                                                                              6.94                                ΔQ (mg/g)                                                               Selectivity coefficient α                                                                1.3     4.5    8.3  30.8 48.0                                Overall evaluation                                                                             X       ◯                                                                        ⊚                                                                   ◯                                                                      X                                   ______________________________________                                    

Sample 12 obtained by using a lower heat treatment temperature at thetime of carbonization than the stipulated temperature of the presentinvention was less in amount of oxygen adsorbed and smaller indifference in adsorbed amount ΔQ as well as in selectivity coefficient αand was not favorable as the molecular sieving carbon. Samples 13, 14and 15 are greater in all of amount of oxygen adsorbed, difference inadsorbed amount ΔQ and selectivity coefficient and are found to bepractical as the molecular sieving carbon and particularly sample 14 isfound to be excellent in characteristics.

Sample 16 obtained by using a higher heat treatment temperature at thetime of carbonization than the stipulated temperature of the presentinvention is greater in selectivity coefficient α, but unfavorablysmaller in amount of oxygen adsorbed and difference in adsorbed amountΔQ.

EXAMPLE 4

Using a particulate molecular sieving carbon prepared in like manner aswith sample 14 in Example 3, experiment with the separation of nitrogenand oxygen in the air was carried out by the pressure swing adsorptionmethod (PSA).

A schematic diagram of PSA apparatus used in the instant experiment wasshown in FIG. 4. The size of the adsorption tower was 50 φ in innerdiameter×1,000 mmL, and the said molecular sieving carbons (specificsurface ara 163 m² /g) were packed in two adsorption towers. Theirpacking density was 0.58 g/cm³.

First, air compressed by a compressor was forwarded to the adsorptiontowers, pressure at the time of adsorption was set at 4 kgf/cm² -G ingauge pressure and desorption (evacuation) regeneration was effected bydepressurizing down to about 100 torr by means of a vacuum pump. PSAoperation was carried out in 5 steps of pressure equalization(elevation)--adsorption--pressure equalization(reduction)--evacuation--pressure elevation, and switchovers of therespective steps were effected by automated control over electromagneticvalves by a sequencer. PSA operation conditions were indicated in Table4.

In the instant experiment purity of the product nitrogen gas was 99.9%(N₂ +Ar) with its take-out amount of 1 l/min. and 99.7% with 2 l/min.

                                      TABLE 4                                     __________________________________________________________________________    30 seconds  60 seconds                                                                           10 seconds                                                                           30 seconds                                                                           60 seconds                                                                           10 seconds                            __________________________________________________________________________    Adsorp-                                                                            Pressure                                                                             Adsorption                                                                           Pressure                                                                             Evacuation    Pressure                              tion elevation                                                                            (concurrent)                                                                         equalization                                                                         (countercurrent)                                                                            equalization                          tower                                                                              (concurrent)  (reduction)          (elevation)                           (1)                (concurrent)         (concurrent)                          Adsorp-                                                                            Evacuation    Pressure                                                                             Pressure                                                                             Adsorption                                                                           Pressure                              tion (countercurrent)                                                                            equalization                                                                         elevation                                                                            (concurrent)                                                                         equalization                          tower              (elevation)                                                                          (concurrent)  (reduction)                           (2)                (concurrent)         (concurrent)                          __________________________________________________________________________

In FIG. 4: 21 . . . air compressor, 22 . . . air drier, 23, 23a . . .adsorption tower, 24,24a . . . first switching valve, 25,25a . . .inflow path pipe, 26 . . . vacuum pump, 28 . . . suction path pipe,29,29a . . . takeout path pipe, 31 . . . main pipe, 34 . . . reservoirtank, 36 . . . product gas take-out pipe, 27,27a,30,30a, 33,33a, 35,37 .. . switching valve.

EXAMPLE 5

Precursors having the same composition as used in Example 4 werecarbonized for 1 hour at 850° C. in nitrogen atmosphere in like manneras in Example 4, and then successively activated for 10 minutes in asteam atmosphere. A sample taken out after cooling the kiln showed areduction in weight of 5.2% by weight based on the weight of thecarbonized product.

The particulate molecular sieving carbon obtained as the above was 620m² /g in specific surface area and 0.54 g/cm³ in packing density.

The molecular sieving carbons were packed in the same PSA apparatus asused in Example 4 and there was conducted experiment to separate amaterial gas of 70% hydrogen gas and 30% methane by the PSA method.

The material gas kept in pressurized condition by means of compressorwas admitted into adsorption towers and PSA operation was carried out byalternately repeating in the two towers 5 steps of pressure equalization(elevation)--pressure elevation--adsorption--pressure equalization(reduction)--evacuation. Adsorption pressure was set at 5 kgf/cm² -G andregeneration was effected by depressurizing down to about 100 torr bymeans of vacuum pump. PSA operation conditions were indicated in Table5.

In the instant experiment purity of the product hydrogen gas was 99.99%with its take-out amount of 2 l/min. and 99.91% with 4 l/min.

Hydrogen and methane, as mentioned above, could be separated in goodcondition by the particulate molecular sieving carbon obtained in thepresent invention.

                                      TABLE 5                                     __________________________________________________________________________    30 seconds  180 seconds                                                                          10 seconds                                                                           30 seconds                                                                           180 seconds                                                                          10 seconds                            __________________________________________________________________________    Adsorp-                                                                            Pressure                                                                             Adsorption                                                                           Pressure                                                                             Evacuation    Pressure                              tion elevation                                                                            (concurrent)                                                                         equalization                                                                         (countercurrent)                                                                            equalization                          tower                                                                              (concurrent)  (reduction)          (elevation)                           (1)                (concurrent)         (concurrent)                          Adsorp-                                                                            Evacuation    Pressure                                                                             Pressure                                                                             Adsorption                                                                           Pressure                              tion (countercurrent)                                                                            equalization                                                                         elevation                                                                            (concurrent)                                                                         equalization                          tower              (elevation)                                                                          (concurrent)  (reduction)                           (2)                (concurrent)         (concurrent)                          __________________________________________________________________________

What we claim is:
 1. A process for the production of a carbonizedparticulate product of molecular sieving carbon, said carbonizedparticulate product comprising an assembly of contiguous, carbonaceousspheres having a diameter of 0.8 to 120 microns and bonded togetherthree-dimensionally at random with continuous interstitial pathwayshaving an average diameter of 0.1 to 20 microns runningthree-dimensionally at random between a number of said carbonaceousspheres, a plurality of the carbonaceous spheres having microporescommunicating with said pathways, said micropores having an averagediameter of about 10 Å or less and a volume of 0.1 to 0.7 cc/g, saidprocess comprising the steps of:(1) preparing an intimate mixturecomprising(A) a finely-divided thermosetting phenol resin, saidfinely-divided thermosetting phenol resin being specified as(a) finepowder comprising primary spherical particles of a phenol resin having aparticle diameter of 1 to 150 microns, (b) of which at least 50% byweight of said fine powder having a size capable of passing through a100 Tyler mesh sieve, (c) satisfying the following formula derived froman infrared absorption spectrum:

    D.sub.900-1015 /D.sub.1600 =0.2-9.0

    D.sub.890 /D.sub.1600 =0.09-1.0

in the case where in the infrared absorption spectrum by KBr tabletmethod, the absorption intensity of a peak at 1600 cm⁻¹ is expressed asD₁₆₀₀, the absorption intensity of the greatest peak in the range of900-1015 cm⁻¹ as D₉₀₀₋₁₀₁₅, and the absorption intensity of a peak at890 cm⁻¹ as D₈₉₀, and (d) having a solubility in methanol under refluxof 50% by weight or less, (B) a solution of a phenol or melaminethermosetting resin, and (C) a polymer binder selected from polyvinylalcohols and water-soluble or water-swellable cellulose derivatives,said intimate mixture containing 5 to 50 parts by weight (as solids) ofthe solution of the thermosetting resin (B) and 1 to 30 parts by weightof the polymer binder (C) per 100 parts by weight of the finely-dividedthermosetting phenol resin; (2) molding the said intimate mixture into ashaped particulate object; and (3) heat treating the shaped particulateobject at a temperature falling in the range of 500°to 1,100° C. in anon-oxidizing atmosphere to form said carbonized particulate product. 2.The process of claim 1, which additionally comprises a second step ofheat treating the carbonized particulate product at a temperaturefalling in the range of 500°to 1,100° C. under an oxidizing atmosphereuntil the carbonized particulate product is reduced in weight in therange up to 15% by weight.
 3. The process of claim 1 in which thefinely-divided thermosetting phenol resin used in the said step (1) hasa solubility in methanol of 1 to 40% by weight.
 4. The process of claim1 in which in step (1), the intimate mixture further contains, besidescomponents (A), (B) and (C), starch, derivatives or modified substancesthereof, an amount of 5 to 50 parts by weight per 100 parts by weight ofthe finely-divided thermosetting phenol resin (A).
 5. The process ofclaim 1 in which the intimate mixture in step (1) is prepared byintimately mixing the components used in step (1) in the presence ofwater.
 6. The process of claim 5, in which the water is contained in anamount of 5 to 30% by weight based on the intimate mixture (as solids).7. The process of claim 1 in which a columnar or spherical particulatesubstance is formed by molding in step (2).
 8. The process of claim 1 inwhich the non-oxidizing atmosphere in the said step (3) is an atmosphereof a gas selected from nitrogen, argon and helium.
 9. The of claim 1which the temperature is increased at a rate of 5° to 300° C./hr untilthe temperature for the heat treatment in the step (3) is reached. 10.The process of claim 2 in which the oxidizing atmosphere is anatmosphere of a gas selected from carbon dioxide and steam.
 11. Theprocess of claim 1, in which said polymer binder is selected from amongwater-soluble or water-swellable cellulose derivatives.